The present invention relates generally to plate adapters for use with flexible couplings and more specifically to such plate adapters which are used to position and rigidify installed half couplings during installation, evaluation and/or testing of associated operating equipment.
Flexible couplings are commonly used to interconnect driving and driven equipment for transmission of driving forces therebetween while accommodating some degree of misalignment between the respective input and output shafts. One type of such flexible coupling comprises two half couplings, one being connected to each of the output and input shafts of the driving and driven equipment and an interconnecting member extending therebetween. Each of the two half couplings includes a hub secured to the input or output shaft and a sleeve which is connected to the hub by means of a flexible coupling such as a flexible disk pack. A spacer tube serves as the interconnecting member and is secured to each of the opposing sleeves.
In many instances, it is desirable to perform check runs on either the driving or driven equipment independently of each other for various reasons such as to check for vibrations or to check radial run out during installation of the equipment. In order to perform these check runs, it is necessary to secure the half coupling in operative relationship with the shaft and it is also desirable to simulate the weight of the spacer tube and its effect on the center of gravity on the overall coupling. For this purpose, the coupling, manufacture is often requested to provide a plate adapter which is designed to be coupled to both the hub and the sleeve so as to prevent relative movement therebetween.
While existing plate adapters have been satisfactory at relatively low speed rotation, these existing plate adapters have not been completely satisfactory for high speed rotation check runs. During such high speed check runs, such as for example in the range of 5,000 to 15,000 RPM, various nonrepeatable vibrations have been detected. These nonrepeatable vibrations result from slight clearances existing between the plate adapter pilot surfaces and the mating pilot surfaces provided on the coupling, creating unbalanced conditions for the mating parts. At high rotational speeds, any problems resulting from slight clearances may become aggravated due to differential circumferential growth between the mating components. Differential circumferential growth refers to the tendency for a rotating part to increase in size radially outwardly as a result of centrifugal forces exerted thereon during rotation.
The prior art plate adapters employed what may be best described as a slight clearance or loose slip fit annular pilot engagement between the plate adapter and the center hub and an intermediate fit or slight clearance to slight interference fit pilot engagement between the plate adapter and the sleeve with the sleeve pilot surface being located radially outwardly of the plate adapter pilot surface. Because differential circumferential growth is generally greater at greater radial distances, the sleeve will tend to experience greater growth than the plate adapter. Thus, because the mating pilot surface of the sleeve is located radially outwardly from the corresponding pilot surface of the plate adapter, high speed rotation of the assembly will result in a decrease in any slight interference fit or an increase in any slight clearance between the pilot surfaces of the plate adapter and sleeve. As a result, the sleeve may shift very slightly and thus induce a vibration in the overall assembly. Elimination of the clearance induced vibration presents special design and assembly difficulties that have previously not been resolved.
The present invention overcomes the problems associated with the prior art plate adapters by incorporating pilot surfaces on the plate adapter for engagement with both the hub and sleeve which provide for slight interference fits. Further, these pilot surfaces are positioned such that circumferential growth resulting from high speed rotation will operate to increase the interference fit of these pilot surfaces. In this manner, the plate adapter will be able to substantially reduce, if not totally eliminate, these nonrepeatable vibrations encountered during customer check runs of equipment on which the half coupling has been installed. Additionally, the plate adapter of the present invention incorporates an arrangement to enable adjustment of the radial runout of the sleeve thus facilitating alignment of the driving and driven equipment without the need for removal of one or both of the half couplings.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.